Multicolor organic element, method for manufacturing the same, and display using the same

ABSTRACT

A multicolor organic EL element having a light emitting layer containing at least two organic dyes that can act as light emitting center (luminescence center), wherein at least one of said organic dyes is modified so as to change the colors of the light emitted from the element, and a method for manufacturing the element, and a display using the element.

FIELD OF THE INVENTION

[0001] The present invention relates to an organic EL element used as aplanar light source or a display element, a method for manufacturing thesame, and a display using the same.

PRIOR ART

[0002] Organic EL elements having a luminescent (light emitting) layercomposed of an organic film, which can provide large-area, low-voltagedisplay elements, are currently attracting a great deal of attention.Since an element structure having organic laminated layers of differingcarrier transportation capabilities can be effectively used to improvethe efficiency of such an element, an element has been proposed in whichthe positive-hole transfer layer and the luminous electrontransportation layers comprise low-molecular aromatic amine and analuminum chelate complex, respectively [C. W. Tang, Appl. Phys. Lett.,51, p. 913 (1987)]. With an applied voltage of 10 V or less, thiselement can provide high brightness of 1,000 cd/m², which is sufficientfor practical use.

[0003] At present, arbitrary organic dyes are used as a luminescencecenter (a light emitting center) to obtain arbitrary luminescent colorsranging from blue to red in the visible region. Furthermore, an RGBmulticolor display (a display element) can be obtained by closelyarranging picture elements having luminescent colors of red (R), green(G), and blue (B), which are the primary colors, in parallel on the samesubstrate.

[0004] However, in order to use a vacuum evaporation method to producemulticolor display, particularly an RGB multicolor display withdifferent luminescent colors as described above, picture elements withdifferent luminescent colors must be sequentially produced on the samesubstrate using a shadow mask. Thus, compared to monochromaticluminescent picture elements, the above picture elements require a largeamount of time and labor for production due to their small size, makingthem unsuitable for use in the manufacture of high-definition displays.

[0005] To solve these problems, Kido et al. have proposed an emittingelement section that is adapted for white that is prepared in a contactprint, but which can provide multiple colors by combining the elementwith a color filter, obviating an arrangement of EL elements over verysmall intervals or a preparation of elements having differentluminescent colors [J. Kido, K. Nagai, Appl. Phys., Vol. 63, pp. 1026 to1029 (1994)]. This method puts a color filter between a transparentsubstrate and a transparent electrode of material such as indium-tinoxide (ITO) in order to modulate emissions from an organic luminescentlayer sandwiched between the ITO and a rear electrode.

[0006] A group at Idemitsu Kosan Co. has also proposed a combination ofa blue-emitting element and a color-converting layer, in order toconvert blue into green or red to arrange RGB picture elements (NikkeiElectronics, January, pp. 102, 1996). This method inserts a fluorescentcolor-converting layer between the ITO and the transparent substrate toconvert blue light generated in the luminescent layer into green and redlight.

[0007] Despite their simplicity, arrangements based on the color filteror blue color-converting methods are inefficient, due tophoto-absorption losses resulting from the color filter or to conversionlosses resulting from the color-converting layer.

OBJECT OF THE INVENTION

[0008] This invention provides a solution to these problems, with theobjective of creating an organic EL element that can providehigh-luminous efficiency and is capable of easily providing multiplecolors. The objectives also include a manufacturing method of suchelements and the creation of a display incorporating such elements.

DISCLOSURE OF THE INVENTION

[0009] To attain said objects, an organic EL element according to thisinvention uses two or more types of organic dyes that can act as lightemitting centers. In attempting to manufacture this element, wediscovered that an organic light emitting dye layer may be partiallyirradiated with electromagnetic radiation (light) to modify one or moredye types through photo-oxidation or photolysis to keep the dyes fromfunctioning fully as light emitting centers, or to change the colors oflight emitted, thereby allowing the production of differing colors atirradiated and non-irradiated portions. The electromagnetic radiationused in this invention has a vacuum frequency of about 10⁻¹⁷ to 10⁵ mand includes the τ-rays, X-rays, ultraviolet radiation, visibleradiation, and infrared radiation and is in particular preferablyultraviolet radiation or visible radiation.

[0010] A first aspect of this invention involves a multicolor organic ELelement, characterized in that the element includes a light emittinglayer (a luminescent layer) containing at least two or more kinds oforganic dyes acting as light emitting centers (luminescence centers) inwhich at least one of the organic element kinds is modified to changethe colors of the light emitted by the element. The light emitting layermay consist of one or many layers.

[0011] A second aspect of this invention involves a method formanufacturing a multicolor organic EL element, involving the formationof a light emitting layer containing at least two kinds of organic dyesacting as light emitting centers, and the partial irradiation of thelight emitting layer with electromagnetic radiation to modify at leastone of these kinds of organic dye.

[0012] A third aspect of this invention involves a method formanufacturing a multicolor organic EL element having one or more lightemitting layers containing organic elements acting as light emittingcenters, characterized in that any light emitting layer is entirely orpartially irradiated with electromagnetic radiation to modify at leastone of these kinds of organic dye present within the irradiated area.

[0013] A fourth aspect of this invention involves a multicolor organicEL element, characterized in that in an organic electroluminescenceelement having a light emitting layer composed of at least one organiccompound layer, the light emitting layer contains three or more kinds oforganic dyes capable of acting as light emitting centers and emittingblue, green, and red light; and in that at least one of these kinds oforganic dye is modified to change the color of the light emitted fromthe corresponding picture element.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a schematic diagram showing a process in (1) to (6) formanufacturing a multicolor organic EL element according to Embodiment 1.

[0015]FIG. 2 shows the emission spectra of elements obtained fromEmbodiments 1 (1) and (2).

[0016]FIG. 3 is a graph showing a luminance-voltage characteristicobtained from Embodiment 1(1).

[0017]FIG. 4 is a graph showing a luminance-voltage characteristicobtained from Embodiment 1(2).

[0018]FIG. 5 is a sectional view of an organic EL element according toEmbodiment 2.

[0019]FIG. 6 is a sectional view of an organic EL element according toEmbodiment 3.

[0020]FIG. 7 is a sectional view of an organic EL element according toEmbodiment 4.

[0021]FIG. 8 is a sectional view illustrating an organic EL elementmanufacturing process according to Embodiment 4 for each of steps A toF.

[0022]FIG. 9 is a simplified view of an organic EL element according toEmbodiment 4, as seen from a glass substrate.

PREFERRED MODES FOR CARRYING OUT THE INVENTION

[0023]FIG. 7 is a schematic diagram showing one embodiment (Embodiment4) of an organic EL element according to this invention. A glasssubstrate (a transparent substrate) 21 is sequentially laminated with atransparent electrode constituting a positive electrode, for example anITO electrode 22; a light emitting layer 23 containing three or morekinds of light emitting dyes; and a rear electrode 24 constituting anegative electrode.

[0024] This particular lamination sequence is only one of severalpossible configurations; other possible configurations include positiveelectrode/positive hole transporting layer/light emitting layer/negativeelectrode, positive electrode/light emitting layer/electron transportinglayer/negative electrode, positive electrode/positive hole transportinglayer/light emitting layer/electron transporting layer/negativeelectrode, positive electrode/positive hole injection layer/lightemitting layer/negative electrode, positive electrode/positive holeinjection layer/positive hole transporting layer/light emittinglayer/negative electrode, and positive electrode/positive hole injectionlayer/positive hole transporting layer/light emitting layer/electrontransporting layer/negative electrode.

[0025]FIG. 8 shows the manufacturing processes for a multicolor organicEL element.

[0026] This invention irradiates with electromagnetic radiation one ormore light emitting layers containing organic dyes capable of acting aslight emitting centers, but any one or all of the layers may beirradiated. In this case, (a) the irradiation strength for the overallsurface may be varied (for example, layers are exposed through a filterhaving locally varying transmittance, as in negative film, or the layersare scanned by varying the strength of light emitted from a fine lightsource); or (b) the layers are partially irradiated using masking.Partial exposure includes, for example, contact exposure using aphoto-mask and projection exposure (that is, partial exposure usinglight focused by a lens or light emitted from a fine light source, orusing such light with a photo-mask).

[0027] In an organic EL element, positive holes are injected into anorganic layer from a positive electrode, namely a positive holeinjection electrode, while electrons are injected into the organic layerfrom a negative electrode, namely an electron injection electrode. Inthe organic layer constituting a light emitting layer, both carriers arerecombined to generate excitons, or excited molecules. By dispersing avery small amount of organic dye in the light emitting layer as dopant(guest), with low excitation energy compared to a compound (host) usedfor the light emitting layer, the transfer of excitation energy enablesthe emission of the host to be modulated into one from the dopant dye.If multiple types of dopant dyes are used, the density of each dopantdye can be adjusted to control the colors of the light emitted from theelement (J. Kido and two others, Appl. Phys. Lett. 67, pp. 2281, 1995).

[0028] This invention provides an element having two or more kinds oforganic dyes that can function as multiple types of light emittingcenters in which any organic dye is partially irradiated withelectromagnetic radiation, such as ultraviolet or visible light,degrading only a specific organic dye in order to modulate the colors ofthe light emitted from the irradiated portion. In this way, a full-colordisplay can be obtained by providing all picture elements on the samesubstrate with red, green, and blue dyes, and using electromagneticradiation to form red, green, and blue emitting picture elements.

[0029] According to this invention, a host compound dispersing dopantdyes that can be used for an-organic EL element emitting two or severalcolors offers an unlimited array of the colors of the emitted light. Thecarrier transporting capability of the host compound is not limited andmay transport electrons and/or positive holes.

[0030] The general host compound may be composed of anthracene,naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene,fluoroscein, perylene, phthaloperylene, naphthaloperylene, perynone,phthaloperynone, naphthaloperynone, diphenylbutadiene,tetraphenylbutadiene, coumarin, oxadiazole, aldadine, bisbenzoxazoline,bisstyryl, pyrazine, cyclopentadiene, oxine, aminoquinoline, imine,diphenylethylene, vinylanthracene, diaminocarbazole, pyrane, thiopyran,polymethyne, merocyanine, imidazole chelated oxynoid compounds,quinacridone, rubrene, or their derivatives.

[0031] An optical whitening agent composed of benzoxazole,benzothiazole, or benzimidazole is disclosed in Japanese PatentApplication Laid Open No. 59-194393, among others. The agents mayinclude benzoxazoles such as2,5-bis(5,7-di-t-pentyl-2-benzoxazolyl)-1,3,4-thiazole,4,4′-bis(5,7-t-pentyl-2-benzoxazolyl)stilbene,4,4′-bis(5,7-di-t-(2-methyl-2-butyl)-2-benzoxazolyl)stilbene, 2,5-bis(5,7-di-t-pentyl-2-benzoxazolyl)thiophene, 2,5-bis[5-(α,α-dimethyl-benzyl]-2-benzoxazolyl]thiophene, 2,5-bis[5,7-di-(2-methyl-2-butyl)-2-benzoxazolyl]-3,4-diphenylthiophene,2,5-bis (5-methyl-2-benzoxazolyl)thiophene,4,4′-bis(2-benzoxazolyl)biphenyl,5-methyl-2-{2-[4-(5-methyl-2-benzoxazolyl)phenyl]vinyl}benzoxazole,2-[2-(4-chlorophenyl)vinyl]naphtho(1,2-d)oxazole; benzothiazole such as2,2′-(p-phenylene-divinylene)-bisbenzothiazole; and benzimidazoles suchas 2-{2-[4-(2-benzoimidazolyl)phenyl]vinyl}benzimidazole and2-[2-(4-carboxyphenyl)vinyl]benzimidazole.

[0032] A metallic-chelated oxanoid compound is disclosed in JapanesePatent Application Laid Open No. 63-295695, among others. Representativeexamples include 8-hydroxyquinoline metallic complexes such astris(8-quinolinol)aluminum, bis(8-quinolinol)magnesium, bis[benzo(f)-8-quinolinol]zinc, bis(2-methyl-8-quinolinorate)aluminum oxide,tris(8-quinolinol)indium, tris(5-methyl-8-quinolinol)aluminum,8-quinolinol lithium, tris(5-chloro-8-quinolinol)gallium, bis(5-chloro-8-quinolinol)calclum, and poly[zinc(II)-bis-(8-hydroxy-5-quinolinonyl)methane]; anddilithiumepinedolidione.

[0033] The distyrylbenzene compound is disclosed in EP Patent No.0373582, among others. Representative examples include1,4-bis(2-methylstyryl) benzene, 1,4-bis(3-methylstyryl)benzene,1,4-bis(4-methylstyryl)benzene, distyrylbenzene,1,4-bis(2-ethylstyryl)benzene, 1,4-bis(3-ethylstyryl)benzene,1,4-bis(2-methylstyryl)-2-methylbenzene, and1,4-bis(2-methyl-styryl)-2-ethylbenzene.

[0034] The distyrylpyrazine derivative disclosed in Japanese PatentApplication Laid Open No. 2-252793 may also be used as an organic dye.Representative examples include 2,5-bis(4-methystyryl)pyrazine,2,5-bis(4-ethylstyryl)pyrazine, 2,5-bis[2-(1-naphthyl)vinyl]pyrazine,2,5-bis(4-methoxystyryl)pyrazine, 2,5-bis[2-(4-biphenyl)vinyl]pyrazine,and 2,5-bis[2-(1-pyrenyl)vinyl]pyrazine.

[0035] The dimethylidene derivative disclosed in EP Patent No. 388768 orJapanese Patent Application Laid Open No. 3-231970 may be used asmaterial for the organic light emitting layer. Representative examplesinclude 1,4-phenylenedimethylidene, 4,4′-phenylenedimethylidene,2,5-xylirenedimethylidene, 2,6-naphthylenedimethylidene,1,4-biphenylene-dimethylidene, 1,4-p-terephenylenedimethilidene,9,10-anthracenediil-dimethylidene,4,4′-(2,2-di-t-butylphenylvinyl)biphenyl,4,4′-(2,2-diphenylvinyl)biphenyl, and their derivatives.

[0036] Such derivatives include the silanamine derivatives disclosed inJapanese Patent Applications-Laid Open No. 6-49079 and No. 6-293778, themultifunctional styryl compounds disclosed in Japanese PatentApplications Laid Open No. 6-279322 and 6-279323, the oxadiazolederivatives disclosed in Japanese Patent Applications Laid Open No.6-107648 and No. 6-92947, the anthracene compounds disclosed in JapanesePatent Application Laid Open No. 6-206865; the oxynate derivastivesdisclosed in Japanese Patent Application Laid Open No. 6-145146, thetetraphenylbutadiene compounds disclosed in Japanese Patent ApplicationLaid Open No. 4-96990, the organic trifunctional compounds disclosed inJapanese Patent Application Laid Open No. 3-296595, the coumarinderivatives disclosed In Japanese Patent Application Laid Open No.2-191694, the perylene derivatives disclosed in Japanese PatentApplication Laid Open No. 2-196885, naphthalene derivatives disclosed inJapanese Patent Application Laid Open No. 2-255789, the phthaloperynonederivatives disclosed in Japanese Patent Application Laid Open No.2-289676, No. 2-88689 and the styrylamine derivatives disclosed inJapanese Patent Application Laid Open No. 2-250292.

[0037] If the element is used in an R (red), G (green), and B (blue)multicolor display, for example a full-color display, it must be able toprovide the primary colors of the emitted light of red, green, and blue.Thus, an organic compound used as a host material must emit a blue lightor a luminescent light having a higher energy level than blue light(near ultraviolet rays). The emission spectrum of such light has a peakwavelength of 370 to 500 nm.

[0038] The organic compound for such a full color display must provideluminescent light ranging from near-ultraviolet light to blue-greenlight and must be able to transport carriers. In this case, this organiccompound may transport electrons and/or positive holes. An organiccompound for a host meeting these requirements includes a metalliccomplex having as a ligand at least one of polycyclic compounds such asp-terphenyl and quaterphenyl and their derivatives; condensed polycycliccarbohydrates such as naphthalene, tetracene, pyrene, coronene,chrysene, anthracene, diphenylanthracene, naphthacene, and phenanthrene,and their derivatives; condensed heterocyclic compounds such asphenanthroline, vasophenanthroline, phenantolidine, acridine, quinoline,quinoxaline, and phenadine, and their derivatives; and perylene,phthaloperylene, naphthaloperylene, perynone, phthaloperynone,naphthaloperynone, diphenylbutadiene, tetraphenylbutadiene, oxadiazole,triazole, ardadine, bisbenzoxazoline, bisstyryl, pyrazine,cyclopentadiene, vinylanthracene, and carbazole, and their derivatives;and 8-quinolinorate and its derivative.

[0039] The oxadiazole disclosed in Japanese Patent Applications LaidOpen No. 5-202011, No. 7-179394, No. 7-278124, and No. 7-228579, thetriadine disclosed in Japanese Patent Application Laid Open No.7-157473, the stilbene and distyrylallylene derivatives disclosed inJapanese Patent Application Laid Open No. 6-203963, the styrylderivatives disclosed in Japanese Patent Applications Laid Open No.6-132080 and No. 6-88072, and the diolefine derivative disclosed inJapanese Patent Applications Laid Open No. 6-100857 and No. 6-207170.The distyrylbenzene compound is disclosed in, for example, EP Patent No.0373582. Representative examples include 1,4-bis(2-methylstyryl)benzene,1,4-bis (3-methystyryl)benzene, 1,4-bis(4-methylstyryl)benzene,distyrylbenzene, 1,4-bis(2-ethylstyryl)benzene,1,4-bis(3-ethylstyryl)benzene, 1,4-bis(2-methylstyryl)-2-methylbenzene,and 1,4-bis(2-methylstyryl)-2-ethylbenzene.

[0040] The distyrylpyrazine derivatives disclosed in Japanese PatentApplication Laid Open No. 2-252793 can be used as a light emitting layerhost material. Representative examples include2,5-bis(4-methylstyryl)pyrazine, 2,5-bis(4-ethylstyryl)pyrazine,2,5-bis[2-(1-naphthyl)vinyl]pyrazine, 2,5-bis(4-methoxystyryl)pyrazine,2,5-bis[2-(4-biphenyl)vinyl]pyrazine, and2,5-bis[2-(1-pyrenyl)vinyl]pyrazine.

[0041] An optical whitening agent such as benzoxazole, benzothiazole, orbenzimidazole may be used and is disclosed in Japanese PatentApplication Laid Open No. 59-194393. Representative examples includebenzoxazole such as2,5-bis(5,7-di-t-pentfyl-2-benzoxazolyl)-1,3,4-thiazole,4,4′-bis(5,7-t-pentyl-2-benzoxazolyl)stilbene,4,4′-bis[5,7-di(2-methyl-2-butyl)-2-benzoxazolyl]stilbene,2,5-bis(5,7-di-t-pentyl-2-benzoxazolyl)thlophene, 2,5-bis[5-(α,α-dimethylbenzyl)]-2-benzo-xazolyl)]thiophene,2,5-bis[5,7-di-(2-methyl-2-butyl)-2-benzoxazolyl]-3,4-diphenylthiophene,2,5-bis(5-methyl-2-benzoxazolyl)thiophene,4,4′-bis(2-benzoxazolyl)biphenyl,5-methyl-2-{2-[4-(5-methyl-2-benzoxazolyl) phenyl]vinyl}benzoxazole,2-[2-(4-chlorophenyl)vinyl]naphtho(1,2-d)oxazole; benzothiazole such as2,2′-(p-phenylenedivinylene)-bisbenzo-thiazole; and benzimidazole suchas 2-{2-[4-(2-benzimidazolyl)phenyl]vinyl}benzimidazole and2-[2-(4-carboxyphenyl)vinyl]benzimidazole.

[0042] Other materials for an organic light emitting layer include thedimethylidene derivatives disclosed in EP Patent No. 388768 and JapanesePatent Application Laid Open No. 3-231970. Representative examplesinclude 1,4-phenylenedimethylidene, 4,4′-phenylenedimethylidene,2,5-xylylenedimethylidene, 2,6-naphthylenedimethylidene,1,4-biphenylene-dimethylidene, 1,4-p-terephenylenedimethilidene,9,10-anthracenediyldiphenylvinyl)biphenyl,4,4′-(2,2-di-t-butylphenylvinyl)biphenyl,4,4′-(2,2-diphenylvinyl)biphenyl, and their derivatives, the silanaminederivatives disclosed in Japanese Patent Applications Laid Open No.6-49079 and No. 6-293778, the multifunctional styryl compounds disclosedin Japanese Patent Applications Laid Open No. 6-279322 and No. 6-279323,the oxadiazole derivatives disclosed in Japanese Patent ApplicationsLaid Open No. 6-107648 and No. 6-92947, the anthracene compoundsdisclosed in Japanese Patent Application Laid Open No. 6-206865, theoxynate derivatives disclosed in Japanese Patent Application Laid OpenNo. 6-145146, the tetraphenylbutadiene compounds disclosed in JapanesePatent Application Laid Open No. 4-96990, the organic trifunctionalcompounds disclosed in Japanese Patent Application Laid Open No.3-296595, the coumarin derivatives disclosed in Japanese PatentApplication Laid Open No. 2-191694, the perylene derivatives disclosedin Japanese Patent Application Laid Open No. 2-196885, the naphthalenederivatives disclosed in Japanese Patent Application Laid Open No.2-255789, the phthaloperynone derivatives disclosed in Japanese PatentApplication Laid Open No. 2-289676 and No. 2-88689, and the styrylaminederivatives disclosed in Japanese Patent Application Laid Open No.2-250292.

[0043] Organic compounds that may be used as potential light emittinglayer host materials include the arylamine compounds, with the choicenot limited to particular arylamine compounds, but preferably thearylamine compounds disclosed in Japanese Patent Applications Laid OpenNo. 6-25659, No. 6-203963, No. 6-215874, No. 7-145116, No. 7-224012,No.7-157473, No. 8-48656, No. 7-126226, No. 7-188130, No. 8-40995, No.8-40996, No. 8-40997, No. 7-126225, No. 7-101911, and No. 7-97355. Thesecompounds include, for example,N,N,N′,N′-tetraphenyl-4,4′-diaminophenyl, N,N′-diphenyl-N,N′-di(3-methylphenyl)-4,4′-diamino-phenyl,2,2-bis(4-di-p-tolylaminophenyl)propane,N,N,N′,N′-tetra-p-tolyl-4,4′-diaminobiphenyl,bis(4-di-p-tolylaminophenyl)phenylmethane,N,N′-diphenyl-N,N′-di(4-methoxyphenyl)-4,4′-diaminobiphenyl,N,N,N′,N′-tetraphenyl-4,4′-diaminophenylether,4,4′-bis(diphenylamino)quadriphenyl,4-N,N-diphenylamino(2-diphenylvinyl)benzene,3-methoxy-4′-N,N-diphenyl-aminostilbenzene, N-phenylcarbazole,1,1-bis(4-di-p-triaminophenyl)-cyclohexane,1,1-bis(4-di-p-triaminophenyl)-4-phenylcyclohexane,bis-)4-dimethylamino-2-methylphenyl)-phenylmethane,N,N,N-tri(p-tolyl)amine,4-(di-p-tolylamino)-4′-[4(di-p-tolylamino)styryl]stilbene,N,N,N′,N′-tetra-p-tolyl-4,4-diamino-biphenyl,N,N,N′-tetraphenyl-4,4′-diamino-bipheyl N-phenylcarbazole,4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl,4,4″-bis[N-(1-naphthyl)-N-phenyl-amino]p-terphenyl,4,4′-bis[N-(2-naphtyl)-N-phenyl-amino]biphenyl,4,4′-bis[N-(3-acenaphthenyl)-N-phenylamino]biphenyl,1,5-bis[N-(1-naphthyl)-N-phenyl-amino]]naphthalene,4,4′-bis[N-(9-anthryl)-N-phenylamino]biphenyl, 4,4″-bis[N-(1-anthryl)-N-phenylamino]p-terphenyl,4,4′-bis[N-2-phenanthryl]-N-phenyl-amino]-biphenyl,4,4′-bis[N-(8-fluoranethenyl)-N-phenylaminolbiphenyl,4,4′-bis[2-pyrenyl]-N-phenylaminolbiphenyl,4,4′-bis[N-(2-perylenyl)-N-phenylamino]biphenyl,4,4′-bis[N-(1-coronenyl)-N-phenyl-amino]biphenyl,2,6-bis(di-p-tolylamino)naphthalene,2,6-bis[di-(1-naphthyl)amino]naphthalene,2,6-bis[N-(1-naphthyl)-N-(2-naphthyl)amino] naphthalene,4,4″-bis[N,N-di(2-naphthyl)amino]terphenyl, 4,4′-bis{N-phenyl-N-[4-(1-naphthyl)phenyl]amino} biphenyl,4,4″-bis[N-phenyl-N-(2-pyrenyl)amino]biphenyl,2,6-bis[N,N-di(2-naphthyl)amino]fluorene,4,4″-bis)N,N-di-p-tolylamino)terphenyl, andbis(N-1-naphthyl)(N-2-naphthyl)amine. Well-known organic compoundsconventionally used to produce organic EL elements may be used, asrequired.

[0044] The above organic compounds may be dispersed in polymer, orpolymerized; or a polymer such as poly (N-vinylcarbazole) or polysilanemay be used.

[0045] The choice of dopant is not restricted, as long as the dopant isa fluorescent organic compound, including not only the above electrontransporting materials, hole transporting materials, and light emittingmaterials, but also dyes such as coumarin derivatives,dicyanomethylenepyrane derivatives, dicyanomethylenethiopyranederivative, fluoresceine derivatives, perylene derivatives, or porphyrinderivativesthat are well-known as laser dyes.

[0046] The organic compound used for the electron transporting layer maybe in addition to the electron transporting organic compounds found inthe light emitting-layer host materials described above, thematallic-chelate complex compounds disclosed in Japanese PatentApplication Laid Open No. 63-295695, No. 8-22557, No. 8-81472, No.5-9470, and No. 5-17764, particularly the matallic-chelate oxidecompounds, preferably a metallic complex having as a ligand at least oneof 8-quinolinorate such as tris (8-quinolinorate)aluminum,bis(8-quinolinor ate)magnesium, bis [benzo(f)-8-quinolinorate]zinc,bis(2-methyl-8-quinol inorate)aluminum, tris(8-quinolinorate)indium,tris(5-methyl-8-quinolinorate)aluminum, 8-quinolinoratelithium,tris(5-chloro-8-quinolinorate)gallium, andbis(5-chloro-8-quinolinorate)calcium, and their derivatives.

[0047] The positive hole transporting layer may comprise one of thepositive hole transporting organic compounds such as arylamine, includedin the above light emitting-layer host materials. The positivehole-transporting layer may also comprise one the above organiccompounds dispersed in polymer, or polymerized. Alternatively, thislayer may comprise π conjugate polymer such as polyparaphenylenevinyleneor its derivative or a polyalkylthiophene derivative, positive holetransporting non-conjugate polymers represented by poly(N-vinylcarbazole), or sigma conjugate polymers such as polysilane.

[0048] The material used for the positive hole injection layer is leftunrestricted, and may comprise metallic phthalocyanine such as copperphthalocyanine, non-metallic phthalocyanine, carbon membranes, orconductive polymers such as polyaniline. Furthermore, Lewis acid isallowed to act on the above arylamine as an oxidizing agent to formradical cations, which may then be used as a positive hole injectionlayer.

[0049] The electromagnetic wave irradiation method (or exposure method)according to this invention may be either of the contact or projectionexposure methods, using a photo-mask, or another well-known exposuremethod, such as laser beam scanning.

[0050] The electromagnetic radiation according to this invention may bevisible light or light with appropriate energy levels, such asultraviolet radiation, X-rays, or τ-rays.

[0051] The various organic films used in this invention may be obtainedusing well-known film-forming methods, such as the vacuum evaporationmethod, the sputtering method, and the application method.

[0052] In the multicolor organic EL element according to the fourthaspect of this invention, picture elements that are modified so as toemit three luminescent colors including red, green, and blue arearranged in a certain pattern, and the red, green, and blue dots may bearranged in a certain pattern or laminated. For example, an electrode, ared organic layer, an electrode, a green organic layer, an electrode, ablue organic layer, and an electrode must be laminated in this order,thereby requiring different process steps for the respective layers.However, the layers may be formed by arranging the three light-emittingsources for red, green, and blue In a certain pattern and providingelectrodes over them. The latter method has the advantage of requiring avery small number of process steps.

[0053] In an element in which pixels each composed of R, G. and B arearranged in parallel in the horizontal direction, one of the twoelectrodes acts as a signal electrode, while the other acts as ascanning electrode. These electrodes are driven in a time-sharing mannerto form images, thereby providing a so-called passive matrix RGBdot-matrix, or full-color display.

[0054] Further, each picture element of a RGB multicolor element isadded active elements such as a transistor to perform a memory-function,thereby providing an active matrix RGB dot-matrix, or full-colordisplay.

[0055] According to this invention, during an element manufacturingprocess, an organic layer having two or more kinds of dyes that can actas light emitting centers may be irradiated with light to degrade anarbitrary dye in order to modulate the corresponding luminescent coloremitted by the element. Thus, partial irradiation enables a very simplearrangement of elements with different luminescent colors on the samesubstrate. This technique may be used for multicolor display elementsand so on.

[0056] By arranging light emitting picture elements for the primarycolors including red, green, and blue on a substrate as one pixel, thisarrangement may be used as a multicolor or full-color display.

[0057] Embodiments

[0058] This invention is described below exemplified in severalembodiments, but the invention is not limited to these particularembodiments.

[0059] The polymer used in these embodiments of the invention wassynthesized in the following manner. The reaction formula for thispolymer is shown in Formula 1.

[0060] (1) One hundred and twenty (120) ml of DMSO as a solvent wasadded to 10.0 g of N,N′-diphenylbenzidine (29.7 mmol), 8.38 g ofp-fluoronitrobenzene (59.4 mmol), and 4.5 g of cesium fluoride (29.7mmol), and the mixture was stirred in a nitrogen atmosphere at 100° C.for 24 hours. Following reaction, the mixture was poured with stirringinto 2500 ml of cold water to obtain crude crystals ofN,N′-dephenyl-N-(4-nitrophenyl)-1,1′-biphenyl-4,4′-diamine (NTPD).Subsequently, the mixture was dried for 12 hours in a vacuum at 60° C.

[0061] (2) Fourteen point two (14.2) grams of NTPD (31.1 mmol), 12.7 gof iodobenze (62.2 mmol), 21.5 g of potassium carbonate (156 mmol), and9.88 g of activated copper (156 mmol) were mixed, which was then stirredIn a nitrogen atmosphere at 220° C. for 36 hours. Following reaction,the mixture was dissolved In 1,2-dichloroethane, then filtered to removecopper. An evaporator was used to remove 1,2-dichloroethane, and thecolumn chromatography method (development solvents: 1,2-dichloroethane:n-hexane=1:1, Rf=0.52) was used to purify the mixture to obtain N,N′-diphenyl-N-(4-nitrophenyl)-N′-(phenyl)-1,1′-biphenyl-4,4′-diamine(NPTPD).

[0062] (3) One hundred and forty (140.0) ml of DMF was added to 3.50 gof NPTPD (9.19 mmol) and 1.83 g of 5% palladium/carbon to reduce thenitro group in a hydrogen atmosphere at room temperature and normalpressure. Following reaction, the mixture was filtered to remove thepalladium/carbon, and the filtrate was poured into cold water (1800 ml)with stirring, thereby obtaining crude crystals ofN,N′-diphenyl-N-)4-aminophenyl)-N′-(phenyl)-1,1′-biphenyl-4,4′-diamine(APTPD).

[0063] (4) Two point sixty three (2.63) grams of APTPD (5.04 mmol) and0.51 g of triethylamine (5.04 mmol) were dissolved in 40 ml of benzene,and 0.79 g of methacrylic acid chloride (7.56 mmol) diluted in 5.0 ml ofbenzene was added dropwise to the mixture as the mixture was stirred at10° C. The mixture was left to react for 36 hours. Following reaction,the mixture was filtered to remove triethylamine hydrochloride. Themixture was then washed, using 1N HCl, 1N NaOH, and water, in thisorder, and dried overnight over anhydrous magnesium sulfate. Anevaporator was used to remove the solvent to obtain crude crystals ofN-substituted methacrylamide containing triphenyldiamine (TPDMA).Subsequently, the column chromatography method (development solvent:1,2-dichloroethane, Rf=0.50) was used to purify the crystal (yield:74.4%, 2.14 g), and a solvent mixture of benzene and cyclohexane wasused for recrystallization to obtain white needle-shaped crystals.

[0064] Yield: 38.5% (2.04 g)

[0065] Melting point: 175.5 to 176.2° C.

[0066] IR (KBr, cm⁻¹: 3400, 1664, 1593 (CONH), 3000 (CH₃), 1637 (CH₂=C)

[0067]¹H NMR (270 MHz, CDCl₃, TMS): δ (ppm)=2.0 (S, 3H, CH₃), 5.4 (S,1H, CH₂), 5.8 (S, 1H, CH₂), 6.9-7.5 (m, 27H, Ar)

[0068] Elemental analysis (as C₄₀H₃₃N₃O₁) Analyzed value: C 84.23%, H6.08%, N 7.06% Calculated value: C 84.03%, H 5.82%, N 7.35%

[0069] (5) One point thirteen (1.13) g of TPDMA (1.98 mmol) and 0.0321 gof azoisobutylonitrile (AIBN) (0.198 mmol) as a starting agent weredissolved in 14.0 ml of benzene as a solvent in an eggplant-type flaskwith a stopcock. After freezing and de-airing, the mixture was left toreact at 60° C. for 48 hours. Following reaction, the mixture was pouredinto methanol (1/20) to precipitate an N-substituted methacrylamidepolymer (PTPDMA) containing triphenyldiamine. Precipitation was repeatedfive times to purify the mixture (benzene/methanol). The structure waschecked using IR spectra, ¹H NMR spectra, and elemental analysis.Polymerization reaction was confirmed through the loss of a peak basedon protons in a double bond of δ (ppm)=5.4(S, 1H, CH₂) and 5.8 (S, 1H,CH₂) in ¹H NMR.

[0070] Yield: 94.4% (1.07 g)

[0071] Weight average molecular weight: 2.7×10⁴ [DMF (LiBr), reducedpolystyrene]

[0072]¹H NMR (270 MHz, CDCl₃, TMS): δ (ppm)=1.3 (S, 3H, CH₃), 2.1 (S,2H, CH₂), 6.6-7.6 (m, 27H, Ar)

[0073] Elemental analysis value (as C₄₀H₃₃N₃O₁) Analyzed value: C83.16%, H 5.93%, N 7.33% Calculated value: C 84.03%, H 5.82%, N 7.35%

[0074]

[0075] Embodiment 1

[0076] (1) No irradiation

[0077]FIG. 1 is a sectional view illustrating a manufacturing processaccording to one embodiment of this Invention. Reference number 1designates a glass substrate on which ITO (indium-tin oxide) 2 of sheetresistance 15 Ω/□ is coated. A solution in 1,2-dichloroethane of polymerPTPDMA synthesized as described above, which has positive transportingcapability, emits a blue-purple light, containing 1 wt. %, 3 wt. %, 5wt. %, or 7 wt. % of rubrene based on the PTPDMA, which emits a yellowlight and has the following formula:

[0078] was used to form a polymer layer 3 (rubrene-dispersed PTPDMAlayer) of 600 Å thickness on the ITO by means of spin-coating.

[0079] A tris(8-quinolinolate)aluminum complex layer (hereafter referredto as Alq) 4 with green emission and expressed by the following formula:

[0080] was formed on said polymer layer 3 as an electron transport layer4 by depositing the material up to 400 Å in a vacuum of 10⁻⁵ Torr.Finally, in the same vacuum, Mg and Ag (10:1) were co-deposited up to2000 Å as a rear electrode 5, acting as a negative electrode. Thelight-emitting area was 0.5 cm×0.5 cm.

[0081] In these organic EL elements, a direct current voltage wasapplied to produce emission from the light emitting layer, using ITO andMg:Ag, respectively, as positive and negative electrodes. Theluminescence was measured using Topcon Luminescence Meter BM-8. Yellowemission from this element was observed through a glass surface.Emission spectra obtained from the elements containing 1 wt. %, 3 wt. %,5 wt. %, and 7 wt. % of rubrene shown in FIGS. 2(a), (b), (c), and (d),respectively, indicate that the rubrene dispersed in PTPDMA functions asa light emitting center (a luminescence center) in this elementstructure. FIG. 3 shows the luminescence-voltage characteristic obtained(in the figure, the triangular symbol indicates 1 wt. % of rubrene, therectangular symbol indicates 3 wt. % of rubrene, the white circularsymbol with a cross indicates 5 wt. % of rubrene, and the square symbolwith a cross indicates 7 wt. % of rubrene). As an initialcharacteristic, a yellow emission of up to 900 cd/m² was obtained at 12V.

[0082] (2) Irradiation of the overall surface

[0083] Next, the polymer layer 3 containing 3 wt. % of rubrene dispersedin polymer was formed on the ITO 2 on the glass substrate 1 up to 600 Åin a similar manner, and the overall surface was irradiated with 240mJ/cm² of i-line produced by a high-pressure mercury lamp in the air. Asin the above elements, the electron transport layer 4 was formed bydepositing Alq on the polymer layer 3 up to 400 Å under a vacuum of 10⁻⁵Torr. In the same vacuum, Mg and Ag (10:1) were co-deposited up to 2000Å as a rear electrode, which acted as a negative electrode 5. Thelight-emitting area was 0.5 cm×0.5 cm.

[0084] In this organic EL element, a direct current was applied toproduce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. FIG. 2 (e) indicatesthat the luminescent color was green, and was thus emitted from Alq, andthat rubrene did not emit light. FIG. 4 shows the luminescence-voltagecharacteristic obtained. As an initial characteristic, a green emissionof up to 9000 cd/m² was obtained at about 10 V.

[0085] (3) Partial irradiation

[0086] Next, the polymer layer 3 containing 3 wt. % of rubrene dispersedin polymer was formed on the ITO 2 on the glass substrate 1 up to 600 Åin a similar manner [see FIG. 1(1) and (2)]. A photo-mask 9 was placedon the polymer surface, and the element was partially irradiated with240 mJ/cm² of i-line produced by a high-pressure mercury lamp in the air[see FIG. 1(3)]. As in the above element, the electron transport layer 4was formed by depositing Alq on polymer layer 3 up to 400 Å in a vacuumof 10⁻⁵ Torr [see FIG. 1(4)]. Mg and Ag (10:1) were co-deposited up to2000 Å under the same vacuum with the rear electrode 5, acting as anegative electrode [see FIG. 1(5)]. The light-emitting area was 0.5cm×0.5 cm.

[0087] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. The unexposed portionemitted a green light, whereas the exposed area emitted a yellow light.This element is a multicolor display element having differentluminescent colors on the same substrate (see the photographs includedin the submitted documents).

[0088] Embodiment 2

[0089] (1) No irradiation

[0090]FIG. 5 is a sectional view of Embodiment 2. Reference number 1designates a glass substrate on which ITO (indium-tin oxide) 2 of sheetresistance 15 Ω/□ is coated. A positive hole-transport layer 6 wasformed on the ITO by depositing N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (hereafter referred to asTPD) which has a positive hole transporting capability and has thefollowing formula

[0091] up to 400 Å thickness in a vacuum of 10⁻⁶ Torr. Next, anAlq-rubrene layer 7 was formed as an electron transporting lightemitting layer 7 by depositing Alq and rubrene thereon up to 600 Å in avacuum of 10⁻⁵ Torr., so that the ratio of Alq to rubrene was 97 wt. %and 3 wt. %. Finally, Mg and Ag (10:1) were co-deposited up to 2000 Åunder the same vacuum, as a rear electrode 5, acting as a negativeelectrode. The light-emitting area was 0.5 cm×0.5 cm.

[0092] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. A yellow emissionfrom this element was observed through a glass surface. An emissionspectrum obtained from the element indicates that rubrene present in theAlq layer functioned as a light emitting center in this elementstructure.

[0093] (2) Irradiation of the overall surface

[0094] Next, a layer 6 of thickness 400 Å was formed on the ITO 2 on theglass substrate 1 in the same manner as described above, and anAlq-rubrene layer 7 was formed by co-depositing Alq and rubrene thereonup to 600 Å in a vacuum of 10⁻⁵ Torr., in the same ratio as describedabove. Then, the overall surface was irradiated with 1200 mJ/cm² ofi-line produced by a high-pressure mercury lamp in the air. Mg and Ag(10:1) were co-deposited on the Alq-rubrene layer 7 up to 2000 Å underthe same vacuum, as a rear electrode 5, acting as a negative electrode.The light-emitting area was 0.5 cm×0.5 cm.

[0095] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. It was found that theluminescent color was green, indicating emission from Alq and noemission from the rubrene, due to photo-oxidation.

[0096] (3) Partial irradiation

[0097] Next, TPD as a layer 6 of thickness 400 Å was formed on the ITO 2on the glass substrate 1 in the same manner, and an Alq-rubrene layer 7was formed by co-depositing Alq and rubrene thereon up to 600 Å in avacuum of 10⁻⁵ Torr., in the same ratio given above. A photo-mask 9 wasplaced on the polymer surface, and the element was partially irradiatedwith 1200 mJ/cm² of i-line produced by a high-pressure mercury lamp inthe air. As in the above element, Mg and Ag (10:1) were co-deposited upto 2000 Å under the vacuum as rear electrode 5, acting as a negativeelectrode. The light-emitting area was 0.5 cm×0.5 cm.

[0098] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. The exposed portionemitted a green light, indicating Alq, whereas the unexposed areaemitted a yellow light, indicating rubrene. This element is a multicolordisplay element having different luminescent colors on the samesubstrate.

[0099] Embodiment 3

[0100] (1) No irradiation

[0101]FIG. 6 is a sectional view of Embodiment 3. Reference number 1designates a glass substrate on which ITO (indium-tin oxide) 2 of sheetresistance 15 Ω/□ is coated. A 1,2-dichloroethane solution containing 30wt. % of electron-transporting 1,3,4-oxadiazole (PBD), 5 wt. % of1,1,4,4-tetraphenyl-1,3-butadiene (hereafter referred to as TPB) that isa blue-light-emitting dye, and 3 wt. % of rubrene, in apoly-(N-vinylcarbazole) (PVK) capable of transporting positive holes andhaving an emission peak in the blue-purple wavelength region (410 to 420nm) was used to form a polymer film 8 of 1000 Å on the ITP by means ofspin-coating. Finally, a layer 5 of Mg and Ag (10:1) was co-deposited upto 2000 Å under the same vacuum as a negative electrode. Thelight-emitting area was 0.5 cm×0.5 cm.

[0102] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. A yellow emission ofup to 2200 cd/m² was obtained at 16 V as an initial characteristic.Further, from emission spectra, it was confirmed that luminescencecenter was rubrene.

[0103] (2) Irradiation of the overall surface

[0104] Next, the PVK layer 8 containing 30 wt. % of PBD, 5 wt. % of TPB,and 3 wt. % of rubrene was formed on the ITO 2 on the glass substrate 1as described above, and the overall surface was irradiated with 120mJ/cm² of i-line produced by a high-pressure mercury lamp in the air. Mgand Ag (10:1) were co-deposited on the polymer layer 8 up to 2000 Å inan identical vacuum, as a rear electrode 5, acting as a negativeelectrode. The light-emitting area was 0.5 cm×0.5 cm.

[0105] In this organic EL element, a direct current was applied toproduce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. It was found that theluminescent color was blue, and thus produced by TPB, and that rubrenedid not emit light due to photo-oxidation.

[0106] (3) Partial irradiation

[0107] Next, the PVK layer 8 containing 30 wt. % of PBD, 5 wt. % of TPB,and 3 wt. % of rubrene was formed on the ITO 2 on the glass substrate 1in the same manner as described above. A photo-mask 9 was placed on thepolymer surface, and the element was partially irradiated with 120mJ/cm² of i-line produced by a high-pressure mercury lamp in the air. Mgand Ag (10:1) were co-deposited on the polymer layer 8 up to 2000 Åunder identical vacuum, as the rear electrode 5, acting as a negativeelectrode. The light-emitting area was 0.5 cm×0.5 cm.

[0108] In this organic EL element, a direct current voltage was appliedto produce emission from the light emitting layer, using ITO and Mg:Ag,respectively, as positive and negative electrodes. The exposed portionemitted blue light, indicating TPB, whereas the unexposed area emittedyellow light, indicating rubrene. This element is a multicolor displayelement having different luminescent colors on the same substrate.

[0109] Embodiment 4

[0110] (1) (Control)

[0111]FIG. 7 is a sectional view of an embodiment of this invention.Reference number 21 designates a glass substrate on which ITO(indium-tin oxide) 22 of sheet resistance 15 Ω/□ is coated. A1,2-dichloroethane solution containing in poly (N-vinylcarbazole)(hereafter referred to as PVK) capable of transporting positive holes,having a blue-purple emission, and expressed by the following formula

[0112] 30 wt. % of 1,3,4-oxadiazole derivative (PBD) capable oftransporting electrons and expressed by the following formula

[0113] 3 mol % of 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), a blue colordye acting as a dopant dye, 1 mol % of coumarin 6 having green emission,and 1 mol % of Nile Red having red emission were used to form adye-containing polymer film up to 1000 Å by means of spin-coating. Then,Mg and Ag (10:1) were co-deposited up to 2000 Å under the same vacuum,as a rear electrode 5, acting as a negative electrode. Thelight-emitting area was 0.5 cm×0.5 cm.

[0114] In this organic electroluminescent element, a direct currentvoltage was applied to produce emission from the light emitting layer,using ITO and Mg:Ag, respectively, as positive and negative electrodes.A red emission from this element was observed through a glass surface.Thus, it was found that in this element structure, the energy transferbetween dopant dyes caused the energy of the dyes to transfer to NileRed with the lowest excitation energy unit, thereby allowing only NileRed to function as a light emitting center. This result was the same asin the reported elements (J. Kido, H. Shionoya and K. Nagai, Appl. Phys.Lett. 67, 2281 (1995)).

[0115] (2) (Control)

[0116] In a similar manner, a dye-dispersed PVK layer was formed on theITO on the glass substrate up to 1000 Å, and a high-pressure mercurylamp was then used to irradiate the layer with light corresponding to anabsorption band of Nile Red, through a filter in the air, therebysubjecting only Nile Red to photo-oxidation to make it non-luminescent.Then, Mg and Ag (10:1) were co-deposited on the polymer layer up to 2000Å under the same vacuum, as a rear electrode acting as a negativeelectrode. In this organic EL element, a direct current voltage wasapplied to produce emission from the light emitting layer, using ITO andMg:Ag, respectively, as positive and negative electrodes. It was foundthat the luminescent color was green, thus emitted from coumarin 6, andthat Nile Red did not emit light.

[0117] (3) (Control)

[0118] In a similar manner, a dye-dispersed PVK layer was formed on theITO on the glass substrate up to 1000 Å, and a high-pressure mercurylamp was then used to irradiate the layer with light corresponding to anabsorption band of Nile Red, through a filter in the air. Then, thefilter was changed to irradiate the layer with light corresponding to anabsorption band of coumarin 6, thereby subjecting both Nile Red andcoumarin 6 to photo-oxidation to render them non-luminescent. Mg and Ag(10:1) were then co-deposited on the polymer layer up to 2000 Å underthe identical vacuum, as a rear electrode, acting as a negativeelectrode. In this organic EL element, a direct current voltage wasapplied to produce emission from the light emitting layer, using ITO andMg:Ag, respectively, as positive and negative electrodes. It was foundthat the luminescent color was blue, and thus emitted from TPB, and thatcoumarin 6 or Nile Red did not emit light.

[0119] (4) (The present invention)

[0120] Next, 16 striped ITO electrodes (shown at 22) of width 3 mm werearranged on the glass substrate 21 in parallel at equal intervals (seeFIGS. 8 and 9), and a dye-dispersed PVK layer 23 was formed up to 1000 Åin a similar manner (FIG. 8B). Then, a photo-mask was placed on thepolymer surface, and a high-pressure mercury lamp was used to irradiatetwo-thirds of the entire area of the PVK layer 23 with light through afilter in such a way that the layer was illuminated in stripes at anequal interval, thereby modifying only Nile Red (FIG. 8C). Subsequently,one half of the area of the PVK layer 23 in which Nile Red had beenmodified using the photo-mask was Irradiated with light In stripes inorder to modify coumarin (FIG. 8D). Forty-eight striped Mg:Ag electrodes(shown at 24) of width 1 mm were deposited in such a way as to cross theITO electrodes to form a matrix display element (FIGS. 8E and 9). Adirect current voltage was applied to this element using ITO and Mg:Ag,respectively, as positive and negative electrodes. Red, green, and bluelight was observed through a glass substrate. In addition, an imageconsisting of R, G, and B could be displayed by using ITO as a scanningelectrode and Mg:Ag as a signal electrode to cause each picture elementto emit light by means of time-sharing driving.

[0121] With respect to the drive method, an active element such as atransistor may be added to each picture element of an RGB multicolorelement to perform a memory function, thereby providing an active-matrixRGB dot-matrix display, or a full-color display.

What is claimed is:
 1. A multicolor organic EL element having a lightemitting layer containing at least two organic dyes that can act aslight emitting center, wherein at least one of said organic dyes ismodified so as to change the colors of the light emitted from theelement.
 2. A multicolor organic EL element characterized in that, in anorganic electroluminescence element having a light emitting layercomposed of at least one layer of an organic compound, said lightemitting layer contains three or more organic dyes which can act aslight emitting center and which emit at least blue, green, and redlight, and that at least one of said organic dyes is modified so as tochange the colors of the light emitted from the picture elements.
 3. Amulticolor organic EL element charaterized in that, in an organicelectroluminescence element having a light emitting layer composed of atleast one layer of an organic compound, with said layer containing threeor more organic dyes that can act as a light emitting center and thatemit at least blue, green, and red light, and with at least one of saidorganic dyes being modified so as to change the colors of the lightemitted from the picture elements, said the picture elements arearranged so as to emit red, green, and blue light by said modification.4. A multicolor organic EL element wherein said picture elements arearranged horizontally and in parallel.
 5. A passive-matrix-type RGB dotmatrix display, in a multicolor organic EL element according to claim 3wherein each pixel is made up of red, green, and blue picture elements,wherein such pixels are arranged horizontally and in parallel, andwherein the light emitting characteristics of each picture element areindependently controlled with linear sequential scanning.
 6. Anactive-matrix-type RGB dot matrix display, in a multicolor organic ELelement according to claim 3 wherein each pixel is made up of red,green, and blue picture elements, wherein such pixels are arrangedhorizontally and in parallel, and wherein an active element Is added toeach picture element to provide a memory function.